I am trying to model single-phase gas flow in a network of crossing triangular ducts (crossing each other at 90 degrees). To model this geometry,i can use doubly periodic boundary condition (two periodic pairs) on a small section of the complete geometry.The small section consits of the inlet and outlet each for the crossing ducts. The periodicity is in the direction of the flow i.e inlet and outlets of each duct ( of the small scetion) will act as a periodic pair. Now CFX doesn't allow to specify inlet/outlet B.C.'s at the inlets and outlets of the geometry, once they are used to define the periodic pair.

Where can i specify the flow boundary conditions (velocity,pressure)? I know the pressure drop through the geometry. Will this help?

I know, the description might be little confusing. If i would have been able to post the picture of my geometry, it would have been very easy to explain.

I am doing my Ph.D. thesis on this topic and i am stuck at this point. Any answers will be of real help to me.

Thanks,

Swapnil.

I'm also confused by this problem. I dont know whether can I set the pieriodic boundary candition and the inlet and outlet boundary condition on the same pair of boundarys.